81372397 has 2 divisors, whose sum is σ = 81372398. Its totient is φ = 81372396.

The previous prime is 81372373. The next prime is 81372409. The reversal of 81372397 is 79327318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80622441 + 749956 = 8979^2 + 866^2 .

It is a cyclic number.

It is not a de Polignac number, because 81372397 - 2¹⁹ = 80848109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81372997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40686198 + 40686199.

It is an arithmetic number, because the mean of its divisors is an integer number (40686199).

Almost surely, 2^81372397 is an apocalyptic number.

It is an amenable number.

81372397 is a deficient number, since it is larger than the sum of its proper divisors (1).

81372397 is an equidigital number, since it uses as much as digits as its factorization.

81372397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 63504, while the sum is 40.

The square root of 81372397 is about 9020.6649976595. The cubic root of 81372397 is about 433.3369308709.

The spelling of 81372397 in words is "eighty-one million, three hundred seventy-two thousand, three hundred ninety-seven".